I just picked up a 235 53/4 corvette (?)dual exhaust manifold that has a very, very stuck heat raiser and it appears the guys before me worked over the shaft and it will not move, the shaft may be bent way too much. There really is not much room to work on it. Can they be reworked using old parts or can the shaft be cut, the baffle separated from the shaft once out and a new shaft built? Or. Can one cut this raiser out plug the holes and install a heat raiser below the manifold like the V8?s have or some of the later 6?s have? Or
Stucked heat raiser Hey Charles How Your doing ? Heat/cooling + water and rust makes these parts get stucked like they are welded together ! I would suggest that you could heat it up and soak it with penetrant oil , then smack it carefully with the Sharp edge of a welding hammer. Martinius. B.t.w. thanks fore sharing Your chevy truck/car show photos
I agree ; Soak it with KROIL and tap gently with a small hammer , either it'll free up or not . The heat riser is an important thing for those frosty morning drives , it helps to warm up the intake faster and avoid flat spots . That being said , if it's dead you can remove it and braze up the holes easily .
Hi Martinius, This unit is clean and there is no rust, it looks like a nos unit but it is starting to look like a china clipper repop, the shaft had been hit many times with a BFH and mushroomed out on the end that has the spring. I have been able to move it back and forth using very light hits, soaking it with pen. oil, straight edging it,the shaft appears to be bent. The show was great and the cars and truck were also.
Repop ? Are you holding out on us Charles ? . Photographs please . If you can find a two hole flange mount heat riser that'd be fine . I thought (?) the V-8 283 one was a three hole design .
Those heat riser valves are more trouble than they are worth.... 'cause even when you do get them in working order.... they can stick in the closed position at any time & cause real problems. Not much need for a heat riser in the warm southwestern states anyway. I would cut that sucker out & weld up the holes & call it good.... If you are concerned with not looking original.... just cut out the internal baffle & leave the frozen spring & counter balance on the outside for looks. And that is one less thing that can go wrong & you will move more air out the exhaust dumps without the restriction of that valve {even when it's in the open position}. .
Naw, Just was going to have an adapter made to make it work, Here are some photos of the manifold in the vise. I'm leaning on just cutting out the inside if I can not get it working by end od this weekend.
Joe, If by the weekends end this thing is not moving I will cut it off and make it look like it still is being used. Thanks for the idea.
Ye Ole Stock Chevy Show Thread.... And what those VCCA judges at the next event don't know won't hurt them
My Truck is not stock in the purist form, so it does not matter what is under the hood. The judges are the contestants entered in the show. Right now I have the raiser turning but not yet freely as it should. Along with new 7" crystal headlight with 10 amber LED auxiliary/utility lights. Right now I'm thinking of having it ready for the Brothers Show at the end of June and getting all the items I want completed.
As it should be... and I applaud your efforts! Stock is such a relative thing.. they're only "stock" the day you drive them home. From then on it's a little less stock with every maintenance procedure. I've always wondered about the effect of the heat riser on the motor itself, on anything other than an inline motor with a single exhaust manifold. Seems like the additional back pressure on one bank of the motor would not be ideal?
The raiser is not turning good the shaft is bent and I may smack it with with the ball pin a few times before doing the cut out. The uneven pressure is interesting thought with the dual ports however it never seems to have hurt the early corvettes any. Excluding Sunday I will have my hands full most of Saturday and Monday figuring out how I'm going to wire those new front head lights.
Was able to get the riser shaft and baffle separated by grinding and drilling o the welds, the shaft sure did not want to come out the spring end had a bearing on it which was stopping the shaft from coming out as was a small portion of weld I did not get ground down. I?ll take it to get sealed Monday along with my rear bumper. Bumper needs to have the receiver worked over and I want a space for the license plate to sit in along with stop light wells. Below are a few photos of the raiser less manifold and one regular 235 manifold I have as an example if I choose to put it back.
Hi Everybody With a non working heat riser the carb has a tendency to ice up and it runs richer also. I have one on my 1965 CJ5 plow Jeep that is stuck and it ices up the base on the carb and makes for a rough running engine. I also have a street driven CJ2A Willys Jeep with a working heat riser and it runs like a top and the carb doesnt ice up either. I am not an automotive engineer so I am not sure the whole science behind them but what I try is to do is make them as they were intended from the factory...stuff seems to work better. Cant wait to see how yours works out. MikeC
Exhaust Heat Risors Mike ; You are correct but , as mentioned , here in the South West you can get by without it . *if* anyone ever bothers to properly maintain them , they never stick and do indeed help with faster engine warmup from a dead cold start . I use and highly recommend Chrysler's excellent heat risor solvent , it comes in nifty aerosol cans with a snorkel attached and as it has graphite in it , works a treat on any old key locks too .
